Conversion 1.4- : Java Glossary

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Conversion 1.4
This table will help you convert from any of the basic data types to any other in Java 1.4 or earler. This table is also available in a Java version 1.5 or later version. Please report any errors or omissions. This table is also available as an amanuensis Applet or as a download with source code.
Conversion Amanuensis Rounding
Conversion Matrix for Java 1.4- Left Zeros
Conversion Matrix for Java 1.5+ Formatted Output
Primitives Reading Numeric Data
Basic Types StreamTokenizer
Truncation StringTokenizer
byte[] ⇔ String Binary
char[] ⇔ String Metric
Hexadecimal Links
StringBuffers & StringBuilders
JDK 1.4- Convert To
From to: boolean t to: byte b to: /*unsigned*/ byte u to: short s to: char c to: int i to: long n to: float f to: double d to: String g to: Boolean tt to: /*signed*/ Byte bb to: /*unsigned*/ Byte uu to: Short ss to: Character cc to: Integer ii to: Long nn to: Float ff to: Double dd From
boolean t -------- // to byte b from boolean t
b = t?(byte)1:(byte)0;
// to /*unsigned*/ byte u from boolean t
u = t?(byte)1:(byte)0;
// to short s from boolean t
s = t?(short)1:(short)0;
// to char c from boolean t
// to get '0' and '1'
c = t?'1':'0';
// or to get Unicode value 0 or 1
c = t?(char)1:(char)0;
// to int i from boolean t
i = t?1:0;
// to long n from boolean t
n = t?1L:0L;
// to float f from boolean t
f = t?1.0f:0.0f;
// to double d from boolean t
d = t?1.0d:0.0d;
// to String g from boolean t
g = String.valueOf(t);
// to Boolean tt from boolean t
tt = t?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from boolean t
bb = new Byte(t?(byte)1:(byte)0);
// to /*unsigned*/ Byte uu from boolean t
uu = new Byte(t?(byte)1:(byte)0);
// to Short ss from boolean t
ss = new Short(t?(short)1:(short)0);
// to Character cc from boolean t
// to get '0' or '1'
cc = new Character(t?'1':'0');
// or to get Unicode 0 or 1
cc = new Character(t?(char)1:(char)0);
// to Integer ii from boolean t
// best JDK 1.5+
ii = Integer.valueOf(t?1:0);
// or JDK 1.4-
ii = new Integer(t?1:0);
// to Long nn from boolean t
// best JDK 1.5+
nn = Long.valueOf(t?1L:0L);
// or JDK 1.4-
nn = new Long(t?1L:0L);
// to Float ff from boolean t
ff = new Float(t?1.f:0.0f);
// to Double dd from boolean t
dd = new Double(t?1.0d:0.0d);
boolean t
byte b // to boolean t from byte b
t = b!=0;
-------- // to /*unsigned*/ byte u from byte b
u = b;
// to short s from byte b
s = b;
// to char c from byte b
// 9 -> '9'
c = (char)(b + '0');
// or to get Unicode value
c = (char)b;
// to int i from byte b
i = b; // sign extends.
// to long n from byte b
n = b; // sign extends.
// to float f from byte b
f = b;
// to double d from byte b
d = b;
// to String g from byte b
// best for readability
g = Integer.toString(b);
// best for maintainability
g = String.valueOf(b);
// or
g = Integer.toString(b, 7 /* radix */);
// or
g = Integer.toBinaryString(b);
// or
g = Integer.toOctalString(b);
// or
g = Integer.toHexString(b);
// or kludgy and slow on unoptimised Javas
g = "" + b;
// to Boolean tt from byte b
tt = (b!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from byte b
bb = new Byte(b);
// to /*unsigned*/ Byte uu from byte b
uu = new Byte(b);
// to Short ss from byte b
ss = new Short(b); // sign extends
// to Character cc from byte b
// 9 -> '9'
cc = new Character((char)(b + '0'));
// or to get Unicode value
cc = new Character((char)b);
// to Integer ii from byte b
// best JDK 1.5+
ii = Integer.valueOf(b);
// or JDK 1.4-
ii = new Integer(b); // sign extends.
// to Long nn from byte b
// best JDK 1.5+
nn = Long.valueOf(b);
// or JDK 1.4-
nn = new Long(b); // sign extends.
// to Float ff from byte b
ff = new Float(b); // sign extends.
// to Double dd from byte b
dd = new Double(b); // sign extends.
byte b
/*unsigned*/ byte u // to boolean t from /*unsigned*/ byte u
t = u!=0;
// to byte b from /*unsigned*/ byte u
b = u;
-------- // to short s from /*unsigned*/ byte u
s = (short)(u & 0xff);
// to char c from /*unsigned*/ byte u
// 9 -> '9'
c = (char)((u & 0xff) + '0');
// or to get Unicode value
c = (char)(u & 0xff);
// to int i from /*unsigned*/ byte u
i = u & 0xff; // does not sign extend
// to long n from /*unsigned*/ byte u
n = ((long)u) & 0xff; // does not sign extend.
// to float f from /*unsigned*/ byte u
f = u & 0xff; // does not sign extend.
// to double d from /*unsigned*/ byte u
d = u & 0xff; // does not sign extend.
// to String g from /*unsigned*/ byte u
// best for readability
g = Integer.toString(u & 0xff);
// best for maintainability
g = String.valueOf(u & 0xff);
// or
g = Integer.toString(u & 0xff, 7 /* radix */);
// or
g = Integer.toBinaryString(u & 0xff);
// or
g = Integer.toOctalString(u & 0xff);
// or
g = Integer.toHexString(u & 0xff);
// or kludgy and possibly slow
g = "" + (u & 0xff);
// to Boolean tt from /*unsigned*/ byte u
tt = (u!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from /*unsigned*/ byte u
bb = new Byte(u);
// to /*unsigned*/ Byte uu from /*unsigned*/ byte u
uu = new Byte(u);
// to Short ss from /*unsigned*/ byte u
ss = new Short((short)(u & 0xff)); // does not sign extend.
// to Character cc from /*unsigned*/ byte u
// 9 -> '9'
cc = new Character((char)((u & 0xff) + '0'));
// or to get Unicode value
cc = new Character((char)(u & 0xff));
// to Integer ii from /*unsigned*/ byte u
// best JDK 1.5+
ii = Integer.valueOf(u & 0xff);
// or JDK 1.4-
ii = new Integer(u & 0xff); // does not sign extend.
// to Long nn from /*unsigned*/ byte u
// best JDK 1.5+
nn = Long.valueOf(((long)u) & 0xff);
// or JDK 1.4-
nn = new Long(((long)u) & 0xff); // does not sign extend.
// to Float ff from /*unsigned*/ byte u
ff = new Float(((long)u) & 0xff); // does not sign extend.
// to Double dd from /*unsigned*/ byte u
dd = new Double(((long)u) & 0xff); // does not sign extend.
/*unsigned*/ byte u
short s // to boolean t from short s
t = s!=0;
// to byte b from short s
b = (byte)s;
// to /*unsigned*/ byte u from short s
u = (byte)s;
-------- // to char c from short s
// 9 -> '9'
c = (char)(s + '0');
// or to get Unicode value
c = (char)s;
// to int i from short s
i = s;
// to long n from short s
n = s;
// to float f from short s
f = s;
// to double d from short s
d = s;
// to String g from short s
// best for readability
g = Integer.toString(s);
// best for maintainability
g = String.valueOf(s);
// or
g = Integer.toString(s, 7 /* radix */);
// or
g = Integer.toBinaryString(s);
// or
g = Integer.toOctalString(s);
// or
g = Integer.toHexString(s);
// or kludgy and possibly slow
g = "" + s;
// to Boolean tt from short s
tt = (s!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from short s
bb = new Byte((byte)s);
// to /*unsigned*/ Byte uu from short s
uu = new Byte((byte)s);
// to Short ss from short s
ss = new Short(s);
// to Character cc from short s
// 9 -> '9'
cc = new Character((char)(s + '0'));
// or to get Unicode value
cc = new Character((char)s);
// to Integer ii from short s
// best JDK 1.5+
ii = Integer.valueOf(s);
// or JDK 1.4-
ii = new Integer(s);
// to Long nn from short s
// best JDK 1.5+
nn = Long.valueOf(s);
// or JDK 1.4-
nn = new Long(s);
// to Float ff from short s
ff = new Float(s); /* locale-insensitive */
// to Double dd from short s
dd = new Double(s); /* locale-insensitive */
short s
char c // to boolean t from char c
// to convert '0' or '1'
t = c!='0';
// to convert Unicode 0 or 1
t = c!=0;
// to byte b from char c
// international
b = (byte)Character.digit(c, 10 /* radix */);
// fastest '9' -> 9
b = (byte)(c - '0');
// or to get Unicode value
b = (byte)c;
// to /*unsigned*/ byte u from char c
// international
u = (byte)Character.digit(c, 10 /* radix */);
// fastest '9' -> 9
u = (byte)(c - '0');
// or to get Unicode value
u = (byte)c;
// to short s from char c
// international
s = (short)Character.digit(c, 10 /* radix */);
// fastest '9' -> 9
s = (short)(c - '0');
// or to get Unicode value
s = (short)c;
-------- // to int i from char c
// international
i = Character.digit(c, 10 /* radix */);
// fastest '9' -> 9
i = c - '0';
// or to get Unicode value
i = c; // does not sign extend.
// to long n from char c
// international
n = Character.digit(c, 10 /* radix */);
// fastest '9' -> 9
n = c - '0';
// or to get Unicode value
n = c; // does not sign extend.
// to float f from char c
f = c; // does not sign extend.
// to double d from char c
d = c; // does not sign extend.
// to String g from char c
g = String.valueOf(c);
// to Boolean tt from char c
// for '0' or '1'
tt = (c!='0')?Boolean.TRUE:Boolean.FALSE;
// or for Unicode 0 or 1
tt = (c!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from char c
bb = new Byte((byte)c);
// to /*unsigned*/ Byte uu from char c
uu = new Byte((byte)c);
// to Short ss from char c
// international
ss = new Short((short)Character.digit(c, 10 /* radix */));
// fastest '9' -> 9
ss = new Short((short)(c - '0'));
// or to get Unicode value
ss = new Short((short)c);
// to Character cc from char c
cc = new Character(c);
// to Integer ii from char c
// international, JDK 1.5+
ii = Integer.valueOf(Character.digit(c, 10 /* radix */));
// fastest '9' -> 9, JDK 1.5+
ii = Integer.valueOf(c - '0');
// or to get Unicode value JDK 1.5+
ii = Integer.valueOf(c);
// international, JDK 1.4-
ii = new Integer(Character.digit(c, 10 /* radix */));
// fastest '9' -> 9, JDK 1.4-
ii = new Integer(c - '0');
// or to get Unicode value JDK 1.4-
ii = new Integer(c);
// to Long nn from char c
// international, JDK 1.5+
nn = Long.valueOf(Character.digit(c, 10 /* radix */));
// fastest '9' -> 9, JDK 1.5+
nn = Long.valueOf(c - '0');
// or to get Unicode value JDK 1.5+
nn = Long.valueOf(c);// international, JDK 1.4-
nn = new Long(Character.digit(c, 10 /* radix */));
// fastest '9' -> 9, JDK 1.4-
nn = new Long(c - '0');
// or to get Unicode value JDK 1.4-
nn = new Long(c);
// to Float ff from char c
ff = new Float(c); // does not sign extend.
// to Double dd from char c
dd = new Double(c); // does not sign extend.
char c
int i // to boolean t from int i
t = i!=0;
// to byte b from int i
b = (byte)i;
// to /*unsigned*/ byte u from int i
u = (byte)i;
// to short s from int i
s = (short)i;
// to char c from int i
// 9 -> '9'
c = (char)(i + '0');
// or to get Unicode value
c = (char)i;
-------- // to long n from int i
n = i;
// to float f from int i
f = i;
// to construct a float out of IEEE bits
f = Float.intBitsToFloat(i);
// to double d from int i
d = i;
// to String g from int i
// best for readability
g = Integer.toString(i);
// best for maintainability
g = String.valueOf(i);
// or
g = Integer.toString(i, 7 /* radix */);
// or
g = Integer.toBinaryString(i);
// or
g = Integer.toOctalString(i);
// or
g = Integer.toHexString(i);
// or kludgy and possibly slow
g = "" + i;
// to Boolean tt from int i
tt = (i!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from int i
bb = new Byte((byte)i);
// to /*unsigned*/ Byte uu from int i
uu = new Byte((byte)i);
// to Short ss from int i
ss = new Short((short)i);
// to Character cc from int i
// 9 -> '9'
cc = new Character((char)(i + '0'));
// or to get Unicode value
cc = new Character((char)i);
// to Integer ii from int i
// best JDK 1.5+
ii = Integer.valueOf(i);
// or JDK 1.4-
ii = new Integer(i);
// to Long nn from int i
// best JDK 1.5+
nn = Long.valueOf(i);
// or JDK 1.4-
nn = new Long(i);
// to Float ff from int i
ff = new Float(i);
// to Double dd from int i
dd = new Double(i);
int i
long n // to boolean t from long n
t = n!=0;
// to byte b from long n
b = (byte)n;
// to /*unsigned*/ byte u from long n
u = (byte)n;
// to short s from long n
s = (short)n;
// to char c from long n
// 9 -> '9'
c = (char)(n + '0');
// or to get Unicode value
c = (char)n;
// to int i from long n
i = (int)n;
-------- // to float f from long n
f = n;
// to double d from long n
d = n;
// to construct a double out of IEEE bits
d = Double.longBitsToDouble (n);
// to String g from long n
// best for readability
g = Long.toString(n);
// best for maintainability
g = String.valueOf(n);
// or
g = Long.toString(n, 7 /* radix */);
// or
g = Long.toBinaryString(n);
// or
g = Long.toOctalString(n);
// or
g = Long.toHexString(n);
// or kludgy and possibly slow
g = "" + n;
// to Boolean tt from long n
tt = (n!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from long n
bb = new Byte((byte)n);
// to /*unsigned*/ Byte uu from long n
uu = new Byte((byte)n);
// to Short ss from long n
ss = new Short((short)n);
// to Character cc from long n
// 9 -> '9'
cc = new Character((char)(n + '0'));
// or to get Unicode value
cc = new Character((char)n);
// to Integer ii from long n
// best JDK 1.5+
ii = Integer.valueOf((int)n);
// or JDK 1.4-
ii = new Integer((int)n);
// to Long nn from long n
// best JDK 1.5+
nn = Long.valueOf(n);
// or JDK 1.4-
nn = new Long(n);
// to Float ff from long n
ff = new Float(n);
// to Double dd from long n
dd = new Double(n);
long n
float f // to boolean t from float f
t = f!=0;
// to byte b from float f
b = (byte)f;
// to /*unsigned*/ byte u from float f
u = (byte)f;
// to short s from float f
s = (short)f;
// to char c from float f
c = (char)f;
// to int i from float f
// best
i = (int)f;
// or
i = Math.round(f);
// or
i = (int)Math.ceil(f);
// or
i = (int)Math.floor(f);
// to see the IEEE bits inside a float
i = Float.floatToIntBits(f);
// to long n from float f
// best
n = (long)f;
// or
n = Math.round(f);
// or
n = (long)Math.ceil(f);
// or
n = (long)Math.floor(f);
-------- // to double d from float f
d = f;
// to String g from float f
// 2 decimal places, rounded, locale-sensitive.
java.text.DecimalFormat df2
= new java.text.DecimalFormat("###,##0.00");
g = df2.format(f);
// or exponential scientific format, locale-sensitive.
java.text.DecimalFormat de
= new java.text.DecimalFormat("0.000000E00");
g = de.format(f);
// or best for readability, no loss of precision, locale-insensitive
g = Float.toString(f);
// or best for maintainability, no loss of precision, locale-insensitive
g = String.valueOf(f);
// to Boolean tt from float f
tt = (f!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from float f
bb = new Byte((byte)f);
// to /*unsigned*/ Byte uu from float f
uu = new Byte((byte)f);
// to Short ss from float f
ss = new Short((short)f);
// to Character cc from float f
cc = new Character((char)f);
// to Integer ii from float f
ii = Integer.valueOf((int)f);
// to Long nn from float f
nn = Long.valueOf((long)f);
// to Float ff from float f
ff = new Float(f);
// to Double dd from float f
dd = new Double(f);
float f
double d // to boolean t from double d
t = d!=0;
// to byte b from double d
b = (byte)d;
// to /*unsigned*/ byte u from double d
u = (byte)d;
// to short s from double d
s = (short)d;
// to char c from double d
c = (char)d;
// to int i from double d
// best
i = (int)d;
// or
i = (int)Math.round(d);
// or
i = (int)Math.ceil(d);
// or
i = (int)Math.floor(d);
// to long n from double d
// best
n = (long)d;
// or
n = Math.round(d);
// or
n = (long)Math.ceil(d);
// or
n = (long)Math.floor(d);
// to see the IEEE bits inside a double
n = Double.doubleToLongBits(d);
// to float f from double d
f = (float)d;
-------- // to String g from double d
// 2 decimal places, rounded, locale-sensitive.
java.text.DecimalFormat df2
= new java.text.DecimalFormat("###,##0.00");
g = df2.format(d);
// or exponential scientific format, locale-sensitive.
java.text.DecimalFormat de
= new java.text.DecimalFormat("0.0000000000E00");
g = de.format(d);
// or best for readability, no loss of precision, locale-insensitive
g = Double.toString(d);
// or best for maintainability, no loss of precision, locale-insensitive
g = String.valueOf(d);
// to Boolean tt from double d
tt = (d!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from double d
bb = new Byte((byte)d);
// to /*unsigned*/ Byte uu from double d
uu = new Byte((byte)d);
// to Short ss from double d
ss = new Short((short)d);
// to Character cc from double d
cc = new Character((char)d);
// to Integer ii from double d
ii = Integer.valueOf((int)d);
// to Long nn from double d
nn = Long.valueOf((long)d);
// to Float ff from double d
ff = new Float(d);
// to Double dd from double d
dd = new Double(d);
double d
String g // to boolean t from String g
t = Boolean.valueOf(g.trim()).booleanValue();
// or
t = g.trim().equalsIgnoreCase("true");
// to byte b from String g
try {
// best
b = (byte)Integer.parseInt(g.trim());
// or
b = (byte)Integer.parseInt(g.trim(), 16 /* radix */);
} catch (NumberFormatException e){/* ... */}
// to /*unsigned*/ byte u from String g
try {
// best
u = (byte)Integer.parseInt(g.trim());
// or
u = (byte)Integer.parseInt(g.trim(), 16 /* radix */);
} catch (NumberFormatException e){/* ... */}
// to short s from String g
try {
// best
s = (short)Integer.parseInt(g.trim());
// or
s = (short)Integer.parseInt(g.trim(), 16 /* radix */);
} catch (NumberFormatException e){/* ... */}
// to char c from String g
try {
// "9" -> '9'
c = g.charAt(0 /* position */);
// or to get Unicode value
c = (char)Integer.parseInt(g.trim());
// or to get Unicode hex value
c = (char)Integer.parseInt(g.trim(), 16 /* radix */);
} catch (NumberFormatException e){/* ... */}
// to int i from String g
try {
// best
i = Integer.parseInt(g.trim());
// or
i = Integer.parseInt(g.trim(), 16 /* radix */);
} catch (NumberFormatException e){/* ... */}
// to long n from String g
try {
n = Long.parseLong(g.trim());
} catch (NumberFormatException e){/* ... */}
// to float f from String g
try {
// best locale-insensitive
f = Float.parseFloat(g.trim());
// or locale-insensitive
f = Float.valueOf(g.trim()).floatValue();
} catch (NumberFormatException e){/* ... */}
// to double d from String g
try {
// best, locale-insensitive
d = Double.parseDouble(g.trim());
// or locale-insensitive
d = Double.valueOf(g.trim()).doubleValue();
} catch (NumberFormatException e){/* ... */}
-------- // to Boolean tt from String g
tt = Boolean.valueOf(g.trim());
// to /*signed*/ Byte bb from String g
try {
// best
bb = new Byte(Byte.parseByte(g.trim()));
// or
bb = new Byte(Byte.parseByte(g.trim(), 16 /* radix */));
// or
bb = new Byte((byte)g.charAt(0 /* position */));
} catch (NumberFormatException e){/* ... */}
// to /*unsigned*/ Byte uu from String g
try {
// best
uu = new Byte(Byte.parseByte(g.trim()));
// or
uu = new Byte(Byte.parseByte(g.trim(), 16 /* radix */));
// or
uu = new Byte((byte)g.charAt(0 /* position */));
} catch (NumberFormatException e){/* ... */}
// to Short ss from String g
try {
// best
ss = new Short(Short.parseShort(g.trim()));
// or
ss = new Short(Short.parseShort(g.trim(), 16 /* radix */));
// or
ss = new Short((short)g.charAt(0 /* position */));
} catch (NumberFormatException e){/* ... */}
// to Character cc from String g
try {
// "9" -> '9'
cc = new Character(g.charAt(0 /* position */));
// or to get Unicode value
cc = new Character((char)Integer.parseInt(g.trim()));
// or to get Unicode hex value
cc = new Character((char)Integer.parseInt(g.trim(), 16 /* radix */));
} catch (NumberFormatException e){/* ... */}
// to Integer ii from String g
try {
// best, caches
ii = Integer.valueOf(g.trim());
// or
ii = new Integer(g.trim());
} catch (NumberFormatException e){/* ... */}
// to Long nn from String g
try {
// best, caches
nn = Long.valueOf(g.trim());
// or
nn = new Long(g.trim());
} catch (NumberFormatException e){/* ... */}
// to Float ff from String g
try {
// best, locale-insensitive.
ff = new Float(g.trim());
// or locale-insensitive
ff = Float.valueOf(g.trim());
} catch (NumberFormatException e){/* ... */}
// to Double dd from String g
try {
// best, locale-insensitive*/
dd = new Double(g);
// or locale-insensitive
dd = Double.valueOf(g);
} catch (NumberFormatException e){/* ... */}
String g
Boolean tt // to boolean t from Boolean tt
t = tt.booleanValue();
// to byte b from Boolean tt
b = tt.booleanValue()?(byte)1:(byte)0;
// to /*unsigned*/ byte u from Boolean tt
u = tt.booleanValue()?(byte)1:(byte)0;
// to short s from Boolean tt
s = tt.booleanValue()?(short)1:(short)0;
// to char c from Boolean tt
// to get '0' and '1'
c = tt.booleanValue()?'1':'0';
// or to get Unicode 0 and 1
c = tt.booleanValue()?(char)1:(char)0;
// to int i from Boolean tt
i = tt.booleanValue()?1:0;
// to long n from Boolean tt
n = tt.booleanValue()?1L:0L;
// to float f from Boolean tt
f = tt.booleanValue()?1.0f:0.0f;
// to double d from Boolean tt
d = tt.booleanValue()?1.0d:0.0d;
// to String g from Boolean tt
g = tt.toString();
-------- // to /*signed*/ Byte bb from Boolean tt
bb = new Byte(tt.booleanValue()?(byte)1:(byte)0);
// to /*unsigned*/ Byte uu from Boolean tt
uu = new Byte(tt.booleanValue()?(byte)1:(byte)0);
// to Short ss from Boolean tt
ss = new Short(tt.booleanValue()?(short)1:(short)0);
// to Character cc from Boolean tt
// to get '0' and '1'
cc = new Character(tt.booleanValue()?'1':'0');
// or to get Unicode 0 or 1
cc = new Character(tt.booleanValue()?(char)1:(char)0);
// to Integer ii from Boolean tt
ii = Integer.valueOf(tt.booleanValue()?1:0);
// to Long nn from Boolean tt
nn = Long.valueOf(tt.booleanValue()?1L:0L);
// to Float ff from Boolean tt
ff = new Float(tt.booleanValue()?1.0f:0.0f);
// to Double dd from Boolean tt
dd = new Double(tt.booleanValue()?1.0d:0.0d);
Boolean tt
/*signed*/ Byte bb // to boolean t from /*signed*/ Byte bb
t = bb.byteValue()!=0;
// to byte b from /*signed*/ Byte bb
b = bb.byteValue();
// to /*unsigned*/ byte u from /*signed*/ Byte bb
u = bb.byteValue();
// to short s from /*signed*/ Byte bb
s = bb.shortValue();
// to char c from /*signed*/ Byte bb
// 9 -> '9'
c = (char)(bb.byteValue() + '0');
// or to get Unicode value
c = (char)bb.byteValue();
// to int i from /*signed*/ Byte bb
i = bb.intValue();
// to long n from /*signed*/ Byte bb
n = bb.longValue();
// to float f from /*signed*/ Byte bb
f = bb.floatValue();
// to double d from /*signed*/ Byte bb
d = bb.doubleValue();
// to String g from /*signed*/ Byte bb
g = bb.toString();
// to Boolean tt from /*signed*/ Byte bb
// best
tt = (bb.byteValue()!='0')?Boolean.TRUE:Boolean.FALSE;
// or
tt = (bb.byteValue()!=0)?Boolean.TRUE:Boolean.FALSE;
-------- // to /*unsigned*/ Byte uu from /*signed*/ Byte bb
uu = bb;
// to Short ss from /*signed*/ Byte bb
ss = new Short(bb.shortValue());
// to Character cc from /*signed*/ Byte bb
// 9 -> '9'
cc = new Character((char)(bb.byteValue() + '0'));
// or to get Unicode value
cc = new Character((char)bb.shortValue());
// to Integer ii from /*signed*/ Byte bb
// best JDK 1.5+
ii = Integer.valueOf(bb.byteValue());
// or JDK 1.4-
ii = new Integer(bb.byteValue());
// to Long nn from /*signed*/ Byte bb
// best JDK 1.5+
nn = Long.valueOf(bb.byteValue());
// or JDK 1.4-
nn = new Long(bb.byteValue());
// to Float ff from /*signed*/ Byte bb
ff = new Float(bb.byteValue());
// to Double dd from /*signed*/ Byte bb
dd = new Double(bb.byteValue());
/*signed*/ Byte bb
/*unsigned*/ Byte uu // to boolean t from /*unsigned*/ Byte uu
t = uu.byteValue()!=0;
// to byte b from /*unsigned*/ Byte uu
b = uu.byteValue();
// to /*unsigned*/ byte u from /*unsigned*/ Byte uu
u = uu.byteValue();
// to short s from /*unsigned*/ Byte uu
s = (short)(uu.intValue() & 0xff);
// to char c from /*unsigned*/ Byte uu
// 9 -> '9'
c = (char)((uu.intValue() + '0') & 0xff);
// or to get Unicode value
c = (char)(uu.intValue() & 0xff);
// to int i from /*unsigned*/ Byte uu
i = uu.intValue() & 0xff;
// to long n from /*unsigned*/ Byte uu
n = uu.longValue() & 0xff;
// to float f from /*unsigned*/ Byte uu
f = (float)(uu.intValue() & 0xff);
// to double d from /*unsigned*/ Byte uu
d = (double)(uu.intValue() & 0xff);
// to String g from /*unsigned*/ Byte uu
g = uu.toString();
// to Boolean tt from /*unsigned*/ Byte uu
// best
tt = (uu.byteValue()!='0')?Boolean.TRUE:Boolean.FALSE;
// or
tt = (uu.byteValue()!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from /*unsigned*/ Byte uu
bb = uu;
-------- // to Short ss from /*unsigned*/ Byte uu
ss = new Short((short)(uu.byteValue() & 0xff));
// to Character cc from /*unsigned*/ Byte uu
// 9 -> '9'
cc = new Character((char)((uu.intValue() + '0') & 0xff));
// or to get Unicode value
cc = new Character((char)(uu.intValue() & 0xff));
// to Integer ii from /*unsigned*/ Byte uu
// best JDK 1.5+
ii = Integer.valueOf(uu.intValue() & 0xff);
// or JDK 1.4-
ii = new Integer(uu.intValue() & 0xff);
// to Long nn from /*unsigned*/ Byte uu
// best JDK 1.5+
nn = Long.valueOf(uu.longValue() & 0xff);
// or JDK 1.4-
nn = new Long(uu.longValue() & 0xff);
// to Float ff from /*unsigned*/ Byte uu
ff = new Float(uu.intValue() & 0xff);
// to Double dd from /*unsigned*/ Byte uu
dd = new Double(uu.intValue() & 0xff);
/*unsigned*/ Byte uu
Short ss // to boolean t from Short ss
t = ss.shortValue()!=0;
// to byte b from Short ss
b = (byte)ss.shortValue();
// to /*unsigned*/ byte u from Short ss
u = (byte)ss.shortValue();
// to short s from Short ss
s = ss.shortValue();
// to char c from Short ss
// 9 -> '9'
c = (char)(ss.shortValue() + '0');
// or to get Unicode value
c = (char)ss.shortValue();
// to int i from Short ss
i = ss.intValue();
// to long n from Short ss
n = ss.longValue();
// to float f from Short ss
f = ss.floatValue();
// to double d from Short ss
d = ss.doubleValue();
// to String g from Short ss
g = ss.toString();
// to Boolean tt from Short ss
// best
tt = (ss.shortValue()!='0')?Boolean.TRUE:Boolean.FALSE;
// or
tt = (ss.shortValue()!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from Short ss
bb = new Byte(ss.byteValue());
// to /*unsigned*/ Byte uu from Short ss
uu = new Byte(ss.byteValue());
-------- // to Character cc from Short ss
// 9 -> '9'
cc = new Character((char)(ss.shortValue() + '0'));
// or to get Unicode value
cc = new Character((char)ss.shortValue());
// to Integer ii from Short ss
// best JDK 1.5+
ii = Integer.valueOf(ss.shortValue());
// or JDK 1.4-
ii = new Integer(ss.shortValue());
// to Long nn from Short ss
// best JDK 1.5+
nn = Long.valueOf(ss.shortValue());
// or JDK 1.4-
nn = new Long(ss.shortValue());
// to Float ff from Short ss
ff = new Float(ss.shortValue());
// to Double dd from Short ss
dd = new Double(ss.shortValue());
Short ss
Character cc // to boolean t from Character cc
// to convert '0' or '1'
t = cc.charValue()!='0';
// to convert Unicode 0 or 1
t = cc.charValue()!=0;
// to byte b from Character cc
// international
b = (byte)Character.digit(cc.charValue(), 10 /* radix */);
// fastest '9' -> 9
b = (byte)(cc.charValue() - '0');
// or to get Unicode value
b = (byte)cc.charValue();
// to /*unsigned*/ byte u from Character cc
// international
u = (byte)Character.digit(cc.charValue(), 10 /* radix */);
// fastest '9' -> 9
u = (byte)(cc.charValue() - '0');
// or to get Unicode value
u = (byte)cc.charValue();
// to short s from Character cc
// international
s = (short)Character.digit(cc.charValue(), 10 /* radix */);
// fastest '9' -> 9
s = (short)(cc.charValue() - '0');
// or to get Unicode value
s = (short)cc.charValue();
// to char c from Character cc
c = cc.charValue();
// to int i from Character cc
// international
i = Character.digit(cc.charValue(), 10 /* radix */);
// fastest '9' -> 9
i = cc.charValue() - '0';
// or to get Unicode value
i = cc.charValue(); // does not sign extend.
// to long n from Character cc
// international
n = Character.digit(cc.charValue(), 10 /* radix */);
// fastest '9' -> 9
n = cc.charValue() - '0';
// or to get Unicode value
n = cc.charValue(); // does not sign extend.
// to float f from Character cc
f = cc.charValue(); // does not sign extend.
// to double d from Character cc
d = cc.charValue(); // does not sign extend.
// to String g from Character cc
g = cc.toString();
// to Boolean tt from Character cc
// for '0' or '1'
tt = (cc.charValue()!='0')?Boolean.TRUE:Boolean.FALSE;
// or for Unicode 0 or 1
tt = (cc.charValue()!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from Character cc
// international
bb = new Byte((byte)Character.digit(cc.charValue(), 10 /* radix */));
// fastest '9' -> 9
bb = new Byte((byte)(cc.charValue() - '0'));
// or to get Unicode value
bb = new Byte((byte)cc.charValue());
// to /*unsigned*/ Byte uu from Character cc
// international
uu = new Byte((byte)Character.digit(cc.charValue(), 10 /* radix */));
// fastest '9' -> 9
uu = new Byte((byte)(cc.charValue() - '0'));
// or to get Unicode value
uu = new Byte((byte)cc.charValue());
// to Short ss from Character cc
// international
ss = new Short((short)Character.digit(cc.charValue(), 10 /* radix */));
// fastest '9' -> 9
ss = new Short((short)(cc.charValue() - '0'));
// or to get Unicode value
ss = new Short((short)cc.charValue());
-------- // to Integer ii from Character cc
// international, JDK 1.5+
ii = Integer.valueOf(Character.digit(cc.charValue(), 10 /* radix */));
// fastest '9' -> 9, JDK 1.5+
ii = Integer.valueOf(cc.charValue() - '0');
// or to get Unicode value JDK 1.5+
ii = Integer.valueOf(cc.charValue());// international, JDK 1.4-
ii = new Integer(Character.digit(cc.charValue(), 10 /* radix */));
// fastest '9' -> 9, JDK 1.4-
ii = new Integer(cc.charValue() - '0');
// or to get Unicode value JDK 1.4-
ii = new Integer(cc.charValue());
// to Long nn from Character cc
// international, JDK 1.5+
nn = Long.valueOf(Character.digit(cc.charValue(), 10 /* radix */));
// fastest '9' -> 9, JDK 1.5+
nn = Long.valueOf(cc.charValue() - '0');
// or to get Unicode value JDK 1.5+
nn = Long.valueOf(cc.charValue());// international, JDK 1.4-
nn = new Long(Character.digit(cc.charValue(), 10 /* radix */));
// fastest '9' -> 9, JDK 1.4-
nn = new Long(cc.charValue() - '0');
// or to get Unicode value JDK 1.4-
nn = new Long(cc.charValue());
// to Float ff from Character cc
ff = new Float(cc.charValue()); // does not sign extend.
// to Double dd from Character cc
dd = new Double(cc.charValue()); // does not sign extend.
Character cc
Integer ii // to boolean t from Integer ii
t = ii.intValue()!=0;
// to byte b from Integer ii
b = ii.byteValue();
// to /*unsigned*/ byte u from Integer ii
u = (byte)(ii.byteValue() & 0xff);
// to short s from Integer ii
s = ii.shortValue();
// to char c from Integer ii
c = (char)ii.intValue();
// to int i from Integer ii
i = ii.intValue();
// to long n from Integer ii
n = ii.longValue();
// to float f from Integer ii
f = ii.floatValue();
// to double d from Integer ii
d = ii.doubleValue();
// to String g from Integer ii
g = ii.toString();
// to Boolean tt from Integer ii
tt = (ii.intValue()!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from Integer ii
bb = new Byte(ii.byteValue());
// to /*unsigned*/ Byte uu from Integer ii
uu = new Byte(ii.byteValue());
// to Short ss from Integer ii
ss = new Short(ii.shortValue());
// to Character cc from Integer ii
// 9 -> '9'
cc = new Character((char)(ii.intValue() + '0'));
// or to get Unicode value
cc = new Character((char)ii.intValue());
-------- // to Long nn from Integer ii
// best JDK 1.5+
nn = Long.valueOf(ii.intValue());
// or JDK 1.4-
nn = new Long(ii.longValue());
// to Float ff from Integer ii
ff = new Float(ii.floatValue());
// to Double dd from Integer ii
dd = new Double(ii.doubleValue());
Integer ii
Long nn // to boolean t from Long nn
t = nn.longValue()!=0;
// to byte b from Long nn
b = (byte)nn.intValue();
// to /*unsigned*/ byte u from Long nn
u = (byte)nn.intValue();
// to short s from Long nn
s = (short)nn.intValue();
// to char c from Long nn
// 9 -> '9'
c = (char)(nn.intValue() + '0');
// or to get Unicode value
c = (char)nn.intValue();
// to int i from Long nn
i = nn.intValue();
// to long n from Long nn
n = nn.longValue();
// to float f from Long nn
f = nn.floatValue();
// to double d from Long nn
d = nn.doubleValue();
// to String g from Long nn
g = nn.toString();
// to Boolean tt from Long nn
tt = (nn.longValue()!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from Long nn
bb = new Byte(nn.byteValue());
// to /*unsigned*/ Byte uu from Long nn
uu = new Byte(nn.byteValue());
// to Short ss from Long nn
ss = new Short(nn.shortValue());
// to Character cc from Long nn
// 9 -> '9'
cc = new Character((char)(nn.intValue() + '0'));
// or to get Unicode value
cc = new Character((char)nn.intValue());
// to Integer ii from Long nn
// best JDK 1.5+
ii = Integer.valueOf(nn.intValue());
// or JDK 1.4-
ii = new Integer(nn.intValue());
-------- // to Float ff from Long nn
ff = new Float(nn.longValue());
// to Double dd from Long nn
dd = new Double(nn.longValue());
Long nn
Float ff // to boolean t from Float ff
t = ff.floatValue()!=0;
// to byte b from Float ff
b = (byte)ff.intValue();
// to /*unsigned*/ byte u from Float ff
u = (byte)ff.intValue();
// to short s from Float ff
s = (short)ff.intValue();
// to char c from Float ff
c = (char)ff.intValue();
// to int i from Float ff
i = ff.intValue();
// to long n from Float ff
n = ff.longValue();
// to float f from Float ff
f = ff.floatValue();
// to double d from Float ff
d = ff.doubleValue();
// to String g from Float ff
// 2 decimal places, rounded, locale-sensitive
java.text.DecimalFormat df2
= new java.text.DecimalFormat("###,##0.00");
g = df2.format(ff.floatValue());
// or exponential scientific format, locale-sensitive.
java.text.DecimalFormat de
= new java.text.DecimalFormat("0.000000E00");
g = de.format(ff.floatValue());
// or best for readability and maintainability, locale-insensitive.
g = ff.toString();
// to Boolean tt from Float ff
tt = (ff.floatValue()!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from Float ff
bb = new Byte(ff.byteValue());
// to /*unsigned*/ Byte uu from Float ff
uu = new Byte(ff.byteValue());
// to Short ss from Float ff
ss = new Short(ff.shortValue());
// to Character cc from Float ff
cc = new Character((char)ff.intValue());
// to Integer ii from Float ff
// best JDK 1.5+
ii = Integer.valueOf(ff.intValue());
// or JDK 1.4-
ii = new Integer(ff.intValue());
// to Long nn from Float ff
// best JDK 1.5+
nn = Long.valueOf(ff.longValue());
// or JDK 1.4-
nn = new Long(ff.longValue());
-------- // to Double dd from Float ff
dd = new Double(ff.floatValue());
Float ff
Double dd // to boolean t from Double dd
t = dd.doubleValue()!=0;
// to byte b from Double dd
b = (byte)dd.intValue();
// to /*unsigned*/ byte u from Double dd
u = (byte)dd.intValue();
// to short s from Double dd
s = (short)dd.intValue();
// to char c from Double dd
c = (char)dd.intValue();
// to int i from Double dd
i = dd.intValue();
// to long n from Double dd
n = dd.longValue();
// to float f from Double dd
f = dd.floatValue();
// to double d from Double dd
d = dd.doubleValue();
// to String g from Double dd
// 2 decimal places, rounded, locale-sensitive
java.text.DecimalFormat df2
= new java.text.DecimalFormat("###,##0.00");
g = df2.format(dd.doubleValue());
// or exponential scientific format, locale sensitive.
java.text.DecimalFormat de
= new java.text.DecimalFormat("0.0000000000E00");
g = de.format(dd.doubleValue());
// or best for readability and maintainability, locale-insensitive
g = dd.toString();
// to Boolean tt from Double dd
tt = (dd.doubleValue()!=0)?Boolean.TRUE:Boolean.FALSE;
// to /*signed*/ Byte bb from Double dd
bb = new Byte(dd.byteValue());
// to /*unsigned*/ Byte uu from Double dd
uu = new Byte(dd.byteValue());
// to Short ss from Double dd
ss = new Short(dd.shortValue());
// to Character cc from Double dd
cc = new Character((char)dd.intValue());
// to Integer ii from Double dd
// best JDK 1.5+
ii = Integer.valueOf(dd.intValue());
// or JDK 1.4-
ii = new Integer(dd.intValue());
// to Long nn from Double dd
// best JDK 1.5+
nn = Long.valueOf(dd.longValue());
// or JDK 1.4-
nn = new Long(dd.longValue());
// to Float ff from Double dd
ff = new Float(dd.floatValue());
-------- Double dd
  to: boolean t to: byte b to: /*unsigned*/ byte u to: short s to: char c to: int i to: long n to: float f to: double d to: String g to: Boolean tt to: /*signed*/ Byte bb to: /*unsigned*/ Byte uu to: Short ss to: Character cc to: Integer ii to: Long nn to: Float ff to: Double dd  

Primitives

Primitive variables include Boolean, char, byte, short, int, long, float and double. Strings, arrays and Objects are not considered primitives.
Java Primitives
Type Signed? Bits Bytes Digits Lowest Highest Mnemonic
Boolean n/a 1 1 1 false true zero/one
char unsigned Unicode 16 2 4:5 '\u0000' [0] aka Character. MIN_VALUE '\uffff' [216-1] aka Character. MAX_VALUE Unicode chars are twice as big as C’s.
byte signed 8 1 2:3 -128 [-27] aka Byte. MIN_VALUE +127 [27-1]aka Byte. MAX_VALUE Bytes are signed, so half the usual 255 range.
short signed 16 2 4:5 -32,768 [-215] aka Short. MIN_VALUE +32,767 [215-1] aka Short. MAX_VALUE 32K
int signed 32 4 9:10 -2,147,483,648 [-231] aka Integer.MIN_VALUE aka -2 gig, roughly -2 billion +2,147,483,647 [231-1] aka Integer. MAX_VALUE. aka 2 gig, roughly 2 billion 2 gig
long signed 64 8 1:19 -9,223,372,036,854,775,807 [-263] aka Long. MIN_VALUE about -9×1018 9,223,372,036,854,775,808 [+263-1] aka Long. MAX_VALUE about 9×1018 9 exabytes, or 9 billion gig
float signed exponent and mantissa 32 4 7 ±1.40129846432481707e-45 aka Float. MIN_VALUE ±3.40282346638528860e+38 aka Float. MAX_VALUE
or roughly ±2127
with about 7 significant digits of accuracy.
A float can exactly represent integers
in the range -224 to +224.
rough, compact float
double signed exponent and mantissa 64 8 16 ±4.94065645841246544e-324 aka Double. MIN_VALUE ±1.79769313486231570e+308 aka Double. MAX_VALUE
or roughly ±21023
with 15 significant digits of accuracy, almost 16 with 15.95 significant digits.
A double can exactly represent integers
in the range -253 to +253.
high precision float

Primitives vs Immutable Wrapper Objects

Contrast that table of primitives, with this table of basic Java types:

Immutable Primitives Immutable Objects
Boolean Boolean
ordinary signed byte Byte
unsigned byte Byte
short Short
char Character
int Integer
long Long
float Float
double Double
char[] String

Truncation

If a long is converted to an int, or an int to a byte, the high order bits are simply truncated. This can result in surprising results including sign reversal.

byte[] ⇔ String

Interconverting byte [] and String is tricky because there is always an implied encoding translation. "8859_1" encoding simply chops the high byte off or pads the high byte with 0s, what newbies erroneously imagine happens all the time.

String s = "abc";

// string -> byte[]
byte [] b = s.getBytes( "8859_1" /* encoding */ );

// byte[] -> String
String t = new String( byteArray, "Cp1252" /* encoding */ );

// subset of byte[] -> String
String t = new String( byteArray, offset, length, "UTF-8" /* encoding */ );

char[] ⇔ String

Interconverting char [] and String is easier because there is no encoding involved. Encoding is about how to represent 16-bit Unicode in 8-bit bytes.

String s = "abc" ;
// string -> char[]
char[] ca = s.toCharArray();
// char[] -> String
String s = new String( ca );

Beware of char[].toString(). It does not convert the character array to String. It prints out the address of the array — not useful for anything. Use new String ( chararray ) instead.

Hexadecimal

The radix feature of the toString and parseInt methods lets you handle hexadecimal numbers. Just set the radix to 16.

StringBuffers & StringBuilders

Strings and StringBuffers can be interconverted, as can Strings and StringBuilders

Rounding

Rounding often surprises because fractions like 0.1 cannot be precisely be represented in IEEE (Institute of Electrical & Electronics Engineers) floating point format. Often you find yourself having to add tiny numbers just prior to printing to get the desired effects.

// Rounding to an integer:
long n = Math.round(d);
double d = Math.rint(d);

// Rounding to two decimal places:
long n = Math.round(d *100.); /* keep as "pennies" */
double d = Math.rint (d *100.)/100.;

floating point for more details.

Left Zeros

The standard conversions give you no leading blanks or leading zeroes. Here is a code snippet to convert an int to a String padded with leading left zeroes. With an obvious modification it would give you lead blanks.

Formatted Output

JDK (Java Development Kit) 1.0.2 has no function like C’s printf that lets you control how many positions and decimal places you want in your output. You have to roll your own.

Java version 1.1 or laterhas formatting picture classes such as java.util.DateFormat, SimpleDateFormat and DecimalFormat.

Formatting is such a common request, you might attain sainthood if you wrote a formatting class that gives you all the power of printf without the overhead of parsing strings for % produce a string, e. g.

Java 1.5+, java.io. PrintWriter. printf, java.io. PrintStream. printf and the java.util. Formatter class give you abilities similar to C’s printf. See printf for more details.

Reading Numeric Data From an ASCII (American Standard Code for Information Interchange) file

Java has no built-in methods for reading data of the form: 123 456,-4.

You have to roll your own method. You may be able to use my CSVReader class. Or use java.io.StreamTokenizer or java.util.StringTokenizer, perhaps in combination with readLine to get your data into strings. StreamTokenizer has bells and whistles to deal with parsing source code, including white space, comments and numbers. StringTokenizer just splits the text up based on delimiter characters. Then use the conversion methods in the table above to convert to integers etc. See below for a simplified examples of how you would do this.

StreamTokenizer Method of Reading Integers From An ASCII File

StringTokenizer Method of Reading Integers From An ASCII file

Binary

Binary is a compact, machine-friendly, human-unintelligible format. For human readable i/o, Java works with Strings of characters. You separately convert these to and from internal binary format e.g. int. See the conversion Amanuensis for how.

Metric Conversions

You can convert metric to Imperial or other measurements by putting expressions in ordinary Google search boxes:


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